Video compression technology is widely used in various products, such as digital set-top boxes (STB), High-Definition TV (HDTV) decoders, digital video disc (DVD) players, digital cameras, network multimedia video applications etc. There are various video encoding methods for compressing digital video content. There are already many video compression standards to standardize the various video encoding methods. Examples of these standards include MPEG-1, MPEG-2 (ITU-T H.262), MPEG-4, ITU-T H.261, ITU-T H.263 and ITU-T H.264.
Video encoding standards such as MPEG standards and the like generally implement data compression through use of various encoding techniques such as time and space prediction, transform and quantization, entropy encoding or the like. Compression in a video encoder typically includes inter-frame prediction and intraframe prediction to improve encoding efficiency. Inter-frame prediction uses time correlation between images of a video, while intraframe prediction uses space correlation of pixels in images of a video.
Inter-frame prediction and intraframe prediction are generally performed on pixel blocks.
For intraframe prediction, it generally uses pixels already reconstructed to extrapolate blocks to be predicted. For example, as for any one of blocks to be encoded in a current image, it uses surrounding pixels that have been reconstructed to perform interpolation in a certain direction, and takes the result after interpolation as a prediction block of the block to be encoded. Difference between the block to be encoded and the prediction block serves as a prediction residual, and the prediction residual is encoded after transform and quantization.